<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>图片上传</title>
</head>
<body>

<div style="border:2px dashed red;">
    <form method="post" enctype="multipart/form-data" action="/face/fileUp">
        <p>
            图片上传前预览：<input type="file" name="faceImg" id="xdaTanFileImg" onchange="xmTanUploadImg(this)" accept="image/*"/>
            <input type="button" value="隐藏图片" onclick="document.getElementById('xmTanImg').style.display = 'none';"/>
            <input type="button" value="显示图片" onclick="document.getElementById('xmTanImg').style.display = 'block';"/>
            <input type="submit" value="upload">
        </p>
        <img id="xmTanImg"/>
        <div id="xmTanDiv"></div>
    </form>
</div>
<hr/>
<script type="text/javascript">
    //判断浏览器是否支持FileReader接口
    if (typeof FileReader == 'undefined') {
        document.getElementById("xmTanDiv").InnerHTML = "<h1>当前浏览器不支持FileReader接口</h1>";
        //使选择控件不可操作
        document.getElementById("xdaTanFileImg").setAttribute("disabled", "disabled");
    }

    //选择图片，马上预览
    function xmTanUploadImg(obj) {
        var file = obj.files[0];

        console.log(obj);
        console.log(file);
        console.log("file.size = " + file.size);  //file.size 单位为byte

        var reader = new FileReader();
        //读取文件过程方法
        reader.onloadstart = function (e) {
            console.log("开始读取....");
        };
        reader.onprogress = function (e) {
            console.log("正在读取中....");
        };
        reader.onabort = function (e) {
            console.log("中断读取....");
        };
        reader.onerror = function (e) {
            console.log("读取异常....");
        };
        reader.onload = function (e) {
            console.log("成功读取....");

            var img = document.getElementById("xmTanImg");
            img.src = e.target.result;
            //或者 img.src = this.result;  //e.target == this
        };
        reader.readAsDataURL(file)
    }
</script>
</body>
</html>
